1. Field of the Invention
The present invention relates generally to the oil and gas industry, particularly reservoir management, and more particularly to apparatus, program product, and methods for acquiring, delivering, controlling, and retaining permanent downhole monitoring system data.
2. Description of Related Art
Advances in technology continue to have a great impact on the petroleum industry. Within the past 20 years, many technologies have transformed the way oil and gas companies manage and/or optimize their operations. One such technology includes permanent downhole monitoring systems (PDHMS), which were introduced over 20 years ago. Early installations included self-contained pressure/temperature gauge module, which had to be retrieved in order to recover data. Some more conventional configurations include wire or fiber-optic connection, which communicate the data to surface units. Others include a network topography which provides such data between downhole sensors and the surface units. Initial methodologies of transferring the data received at the surface to a central computer or monitoring station included use of physical transport and/or transmission over land-based wire lines. A PDHMS surface unit typically is used to collect subsurface sensor performance data, i.e., pressure and temperature gauges. The connection between the surface unit and the subsurface gauges is typically a vendor propriety solution. Connection from the PDHMS surface unit to the host (RTU/SCADA), however, is typically via either standard RS232 or RS485 interfaces.
More recent technologies include utilization of radiowave well data monitoring which can include individual well transmitters that transmit to a remote terminal unit (RTU) that sends the data by UHF radio to an information server or SCADA system, which can then migrate the data over a local communication network to desktops of production engineers. Similar technologies include utilization of global satellite mobile or cellular telephone based communication, which have generally been employed as a backup to provide alerts. Such technologies of remote monitoring of field data can provide wellhead pressure, annuli pressures, etc., both in real-time and on demand, to allow centralized well control.
In order to provide sufficient data to properly monitor and control each well, it is desirable that the PDHMS surface units be capable of collecting subsurface sensor data at short intervals. Recognized by the inventors is that significantly enhanced monitoring and control of can be had by acquiring sensor data, for example, at one second intervals. Conventional PDHMS surface units, however, generally have limited storage capacity and only a single serial interface (e.g., RS-232 serial port). As such, problems encountered with conventional PDHMS surface units include the limited storage capacity resulting in vital reservoir performance data loss, and the limited bandwidth provided by the serial interface resulting in an inability to transmit large data files representing stored data while simultaneously continuing to transmit currently collected data. Additionally, conventional PDHMS surface units generally do not have an effective time synchronization capability with the host computer in order to properly identify stored data stored by such conventional PDHMS surface units. As such, existing systems would or do not tolerate either failure of the host computer/SCADA server/RTU or failure of the network between the host computer/SCADA server and the PDHMS surface units when operating at a high dataflow rate, and thus, do not support such enhanced monitoring and control scheme recognized as extremely advantageous by the inventors.
Specifically, due to such limited storage capacity, limited transmission bandwidth, and lack of time synchronization capability with the host, which can cause insurmountable data conflicts between captured data and the host data that is used for simulation and reservoir optimization, data collected during a communications outage typically must either be discarded out right, or would be discarded by the host system. As such, it has been recognized by the inventors that existing systems do not adequately tolerate network or host failure, and that a network failure or a host failure results in loss of the collected data during the outage period. Additionally, it has been recognized that data lost during the outage or during a PDHMS system capacity/storage capacity overload condition can not be regenerated by conventional systems. Further, it has been recognized by the inventors that even if conventional PDHMS systems were made to have the ability to recover such extensive collected data, such systems could not place such recovered data in the proper sequential order with respect to the data received prior to and after the outage, making the recovered data virtually useless.
Recognized, therefore, by the inventors is the need for an apparatus/system, program product, and methods which provide a PDHMS system having sufficient storage capacity to store downhole process data collected during a downstream communication interruption, an apparatus/system capable of regenerating collected data that is “lost” during an outage or during a capacity overload condition, a PDHMS system which has sufficient bandwidth to allow large recovery file transmissions that do not disrupt real-time data acquisition and transmission of current data, and a PDHMS system which has time synchronization capabilities with the host system to allow for recovering missing data into the proper sequential order.